test2notes

Study Information for Test 2

Contents

1. Some comments

2. What will be on the test

3. Equation sheet

4. Test format

5. Examples of questions

1. Some comments

On problems, it is important to show how you reasoned from the information given in the problem to your final answer. The correct final answer with units is only worth 2-3 points. The remainder of the points are given for the quality of your solution. You need to include the following to receive full credit:

All the information given in the problem with correct units (This may include a diagram)

A statement of what quantity you are trying to find.

State explicitly what physics principle you are using to solve the problem

Solve for the unknown quantity in symbols explicitly before numberic calculations

Then substitute numbers with units and calculate the numeric answer

Extra credit will be given for checks made to see if the answer is reasonable

Be prepared to make reasonable estimations and state your assumptions when solving problems. Be aware of significant digits in your answers. (Keep lots of digits until the final calculation, then round to the appropriate precision.)

Here are some really good tips on test taking from Dr. Richard Felder's website at North Carolina State University.

If you have ANY questions while taking the test, please be sure to ask the instructor. The purpose of the test is not to give you trick problems to catch you in an error. The purpose is to give you an opportunity to "show what you know" ! The test problems are based completely on the reading, the lectures, and the homework. If you understand the main ideas and how to apply them, you'll do well.

2. What will be on the test

Be sure to carefully review your notes, especially when we do things that are not covered very well in the book. Looking over the individual class days linked to the calendar on the class website will also help refresh your memory. Although this test is comprehensive, the test will emphasize material from chapters 3, 4, & 5.

For this test, you should be able to do the following things:

Chapter 1 (Measurement, Estimation, and Units)

Use base SI units and various conversion factors. For example, compute the number of seconds in an hour, day, or year.

Analyze the units and dimensions of equations; use units in numerical calculations.

Make order of magnitude calculations.

Chapter 2 (Concepts and Mathematics of Motion)

Be able to state, use, and differentiate the definitions of position, distance, displacement, speed, velocity, and acceleration.

To learn to analyze the motion of an object by using motion diagrams as a tool.

To learn to identify velocity and acceleration vectors (both direction and relative magnitude) at different points in an objects motion.

To recognize the relationship between the velocity and acceleration vectors when an object is speeding up, slowing down, curving, or at a turning point.

To understand and use the basic ideas of the particle model.

To gain experience with vectors and graphical vector addition and subtraction.

To begin the process of learning to analyze problem statements and to translate the information into other representations.

To obtain a clear understanding of the concepts of position, velocity, and acceleration in one dimension and the relationships between them.

To learn to translate kinematic information between verbal, pictorial, graphical, and algebraic representations.

To learn the basic ideas of calculus (differentiation and integration) and to utilize these ideas both symbolically and graphically.

To solve kinematic problems and to interpret the results

Chapter 3 (Vectors & Coordinate Systems)

Explain the difference between vectors and scalars, giving examples of each

To add and subtract vectors both graphically and using components.

To be able to decompose a vector into it's components and to reassemble vector components into a magnitude and direction. .

To recognize and be able to use the basic unit vectors..

be able to express vectors in two and three dimensions in terms of Cartesian unit vectors i,j,k.

To be able to work with tilted coordinate systems.

To understand and use proper significant figures

Chapter 4 (Motion in two dimensions)

state and use the definitions of 2D position, displacement, average velocity, average acceleration.

state and use use the definitions of 2D instantaneous velocity and acceleration.

solve projectile motion problems using constant acceleration equations in 2D.

use calculus to develop or check equations for displacement, velocity, and acceleration.

sketch velocity and acceleration vectors for uniform circular motion; calculate the magnitude of a from v.

Chapters 5 & 6 Force and Motion

To recognize what does and does not constitute a force
To identify the specific forces acting on an object
To draw a system schema and an accurate free-body diagram of an object
To begin the process of understanding the connection between force and motion
To begin learning how to explain an observation on the basis of physical principles

To distinguish mass, weight, and apparent weight
To learn and use a simple model of friction
To recognize and solve simple equilibrium problems
To be able to describe each of Newton's laws of motion in your own words and provide exampes from real-life situations.
To learn the full strategy for force and motion problems and apply it to the successful solution of problems in single particle dynamics.

3. What you are expected to know and be able to access quickly

Equations:You will need to know the following equations and under what conditions they can be applied. When you do calculations you will typically be expected to start with one of these equations and to derive what you need for the specific problem. See comments in Section 1 above.

Should also know formulas for:

area & circumference of a circle
area & volume for cube & sphere
average speed

Conversions (rules of thumb):

yard => meters
miles => km
inches => cm
kg => lb
quarts => liters

Numbers to know:

your height and weight/mass in English and SI units
The size of your hand
The number of people who live in the Orlando Metropolitan Area
The number of people in the US
The distance from LA to New York
The distance from Orlando to Miami

You will need to be able to derive specific equations you need from these equations listed above. You will be given any additional constants and conversions you need. Unless told otherwise, you may use - 10 m/s^/s for the gravitational constant.

4. Test Format:

Full period on Friday, October 19, 2001

Part I

Group Problem using GOAL Protocol 25 points

Part II

Multiple Choice or short answer question, typically 4-5 parts
           (no explanation required, but no partial credit either)    20 points

Estimation Problem    15 points

Short Essay
( Mainly looking for an answer in words - about a paragraph, but equations, diagrams, and graphs OK. No calculations allowed)    10 points

2 Problems based on Homework and Lecture – 10-20 points each    30 points

Total 100 points

If the overall test average of your entire group is 75% or above, every member of your group will receive a bonus of 5%.

Bonus points for problems 2,4, & 5 are awarded for showing work to check your answer for reasonableness or for using GOAL.

Note: The test will be printed single sided so you should not run out of room. If you need more than a single page, please use the back of the previous problem.

5. Practice Test 2 /

Test 2 from last semester is a viable practice test. Also take a look at problems assigned for homework and problems from Test 1.

Spring 2001 Test 2 solution, Problems 1,2, 3, 4, & 5

6. Some Practice Questions

To test your understanding of key concepts, try the multiple-choice problems here. This NC State website has practice problems for a class similar to ours. Tests 1 & 2 have material relevant to this test. Ignore questions that mention energy or work.

Short essay

This will require a single paragraph answer. Often a drawing or reference to equations will be helpful in your answer. Take care to be very thorough in your discussion.

Discuss the difference between the physical content of the two laws F = ma and F = mg. (Do NOT just give a one sentence statement describing each. Think about what they mean and how they are used. Are they similar in some ways? Are they different in some ways? What I am looking for here is a thoughtful discussion that shows some insight into what these laws mean.)
Discuss what we mean in physics by "a force". How do we know when an object is feeling a force? What kinds of forces are there? Write a brief (one to two page) essay discussing what a physicist means by a "force". Include a discussion of what the different kinds of forces are that we have talked about in this class and some of their properties.
When I release a book in midair it falls to the ground. When I put it on a table, the book stays where it is. Discuss why the book on the table does not fall. How does the table know what to do?
An old Yiddish joke is told about a farmer in Chelm, a town famous for the lack of wisdom of its inhabitants. One day
the farmer was going to the mill to have a bag of wheat ground into flour. He was riding to the mill on his donkey, with the
sack of wheat thrown over the donkey's back behind him. On his way, he met a friend. His friend chastised him. "Look at
you! You must weigh 200 pounds and that sack of flour must weigh 100. That's a very small donkey! Together, you're too
much weight for him to carry!" On his way to the mill the farmer thought about what his friend had said. On his way home,
he passed his friend again, confident that this time the friend would be satisfied. The farmer still rode the donkey, but this
time he carried the 100 pound bag of flour on his own shoulder! Analyze the problem by considering the following simplified picture: two blocks resting on a scale. One block weighs 10 N, the other 25 N.

In case 1 the blocks are arranged on the scale as shown in the figure below.
In case 2 the blocks are arranged as shown on the right. Each system has come to rest.

Homework and Lecture problems

Take a close look at the problems you've been assigned for homework and the problems we have done in class, making sure you can do them all. You should have carefully written-out solutions for all of them. You might want to review the quizzes also.

1. A skier starts from rest at the top of a hill h m tall down a 30.0 degree ski slope with
an acceleration a.

a.) What is her speed at the bottom of the hill?

b.) If the hill was 250 m high and her acceleration down the slope was 4.00 m/s², what was instantaneous speed at the bottom of the hill and her average speed down the slope?c.) At the base of the hill, she continues horizontally for another 250 m before coming to a stop and ending her run. What is her total vector displacement from start to finish?

GOAL Problems

Finally you are leaving Orlando to get a few days of Spring break, but your car breaks down in the middle of nowhere. A tow truck weighing 4000 lbs comes along and agrees to tow your car, which weighs 2000 lbs, to the nearest town. The driver of the truck attaches his cable to your car at an angle of 20 degrees to the horizontal. He tells you that his cable has a strength of 500 lbs. He plans to take 10 seconds to tow your car at a constant acceleration from rest in a straight line along the flat road until he reaches the maximum speed limit of 45 miles/hour. Can the driver carry out his plan? You assume that rolling friction behaves like kinetic friction, and the coefficient of rolling friction between your tires and the road is 0.10.

As Interstate 70 passes through the Rocky Mountains in Colorado, it climbs and descends several thousand feet. Because this is a major truck route, there are ramps inclined at the side of the road on downhills as shown below in case of brake failure. A truck whose breaks have failed will go the ramp using friction and gravity to come to a stop. Assuming that the trucks have a mass of 20 metric tons (1 metric ton = 1000 kg), answer the following questions?
A. What is the steepest ramp angle the ramp can have from horizontal so that the truck does not slide back down once it comes to a stop?
B. If the truck starts up the ramp at 150 km/hr, how far up the ramp does it go?

You are part of a citizen's group evaluating the safety of a high school athletic program. To help judge the diving program you would like to know how fast a diver hits the water in the most complicated dive. The coach has his best diver perform for your group. The diver, after jumping from the high board, moves through the air with a constant acceleration of 9.8 m/s2. Later in the dive, she passes near a lower diving board which is 3.0 m above the water. With your trusty stop watch, you determine that it took 0.20 seconds to enter the water from the time the diver passed the lower board. How fast was she going when she hit the water?

Part I
Group Problem using GOAL Protocol	25 points
Part II
Multiple Choice or short answer question, typically 4-5 parts (no explanation required, but no partial credit either)	20 points
Estimation Problem	15 points
Short Essay ( Mainly looking for an answer in words - about a paragraph, but equations, diagrams, and graphs OK. No calculations allowed)	10 points
2 Problems based on Homework and Lecture – 10-20 points each	30 points
Total	100 points